In a conventional reciprocating internal combustion engine, a cylinder block is provided with a plurality of cylinders therein, each containing a piston and connection means which reciprocates within the cylinder to drive a crankshaft. A cylinder head is positioned on the cylinder block to create a number of combustion chamber zones each of which is associated with one of the cylinders.
The combustion chamber zones include inlet valve means which control through a complete range of power the flow of fuel/air into the cylinder prior to combustion and exhaust valve means for controlling the flow of exhaust gases which result from the combustion. The valve "lift" or "stroke" is the degree of opening of the inlet and exhaust valves. This opening is generally regulated by a valve train means comprising a camshaft containing an eccentric lobe. The lobe has a profile which directly affects the length of opening of the valve. Since the size and configuration of the lobe is static, the motion delivered to the valve for lift or length of stroke will be constant except for minor adjustments of valve lash.
Thus, conventional valve stroke arrangements for internal combustion engines often compromise engine performance as the engine revolutions per minute (RPM) vary. Generally speaking, more powerful engines are designed with a relatively longer stroke camshaft allowing such engines to develop maximum horsepower and torque at higher RPM's with a proportionate reduction in terms of overall fuel economy. Conversely, the more fuel efficient engines generally have a shorter valve stroke camshaft which concentrates horsepower and torque at lower engine RPM's however such engines lack the ability to generate high usable power. Consequently, conventional engine design has the effect of positioning a point of maximum efficiency either higher up or lower down on the RPM scale of the engine.
Variable stroke valve train mechanisms have been proposed in the prior art. U.S. Pat. No. 4,911,124 (Bennett) discloses a device which includes an adjustable fulcrum point which is positioned beneath the valve rocker arm in order to vary the stroke of the cylinder valve. U.S. Pat. No. 4,986,227 (Dewey, III) discloses a device to adjust valve lift in response to engine RPM by designing a rocker arm with a convex fulcrum-engaging top surface. A variable-positioned fulcrum assembly is adjustable along the top surface of the rocker arm to vary valve stroke accordingly. U.S. Pat. No. 4,836,155 (Slagley et al.) discloses a variable duration valve opening mechanism which includes a horizontally shiftable lifter device operating and positioned between the camshaft and the rocker arm. All of the above mentioned prior art devices are either complicated in design, expensive to install or require sophisticated control means to maintain. Further, none of the above mentioned devices interconnect a valve stroke adjustment mechanism with a fuel pre-heater to enhance fuel vaporization.
Prior art fuel pre-heating devices for internal combustion engines are also known. U.S. Pat. No. 4,644,925 (Hoppie et al.) discloses an apparatus for rapidly heating and vaporizing fuel prior to injection into a combustion chamber by directing the fuel through a heat exchange coil disposed within the flow path of the exhaust gases. "Vaporizing" refers to a fuel change from the liquid to the gaseous state without a change in the chemical composition of the molecules. Generally this is done by heating the liquid to atomize it or subdivide into a fine spray. U.S. Pat. No. 3,894,520 (Clawson) discloses a device to vaporize fuel prior to combustion whereby exhaust gases which exit the cylinder are allowed to pass over a conduit containing the fuel to pre-heat the same. Both of the above mentioned fuel pre-heating devices require heat exchange means which are positioned within the path of escaping exhaust gases and at a location remote from the point of gas release. Further, both devices are complicated in construction and require relatively elaborate means to function. Additionally, neither prior art device may be installed after construction of the internal combustion engine. Both require modification of the engine during manufacture. Lastly, neither device controls the amount of pre-heating by adjusting valve stroke for maximum fuel combustion efficiency.
A need has thus existed within the art for providing a mechanism to adjust valve stroke in response to engine RPM's which is highly efficient yet simple in design. Further, no prior art is in existence controls the fuel vaporization rate in response to engine RPM's. In view of the continued instability of current oil supply, as well as the deterioration of the environment from excessive emissions, a need has existed for an internal combustion engine which combines fuel economy, decreased pollutant emissions and increased power.